The invention relates to a voltage supply apparatus for providing a supply voltage for electric devices in an aeroplane cabin.
Voltage supply apparatus in aeroplane cabins, as disclosed in U.S. Pat. No. 3,370,813, usually serve to provide a voltage supply to the passenger for operating electric devices, for example computers, electronic entertainment devices, chargers etc. For this purpose, sockets are arranged in the interior space of the aeroplane cabin, in most cases in the area of a passenger seat or a seating unit, into which the plug of the electric device can be inserted and by means of which the device can be connected to a supply voltage which can be applied to the plug.
In supplying and operating electric devices in an aeroplane, two safety aspects have to be taken into consideration: Firstly, the safety of the passengers has to be assured, and secondly, the electric device must not feed interferences into the electric on-board network of the aeroplane. Because of the safety of the passengers, a DC voltage of up to 30 V is provided on the socket in known voltage supply apparatus. A disadvantage of this is that not every electric device can be operated with a low DC voltage. Furthermore, special connection cables are necessary in current supplies of this kind by means of which the electric device is connected to the socket.
Known are also voltage supply apparatus providing 220/110 V mains voltage for aeroplane passengers' devices so that practically any electric device can be connected by means of its mains plug. The voltage supply is turned on and off by means of a loose-key switch on the socket, the corresponding key being supplied by the flight personnel. In this system, it is neither ensured that the passengers are free from danger from the mains voltage, nor is the aeroplane on-board network secured against interferences from the connected electric devices.